流明中间件关闭错误

Lumen middleware closure error

在Lumen 5.5中,我修改了示例中间件

<?php

namespace App\Http\Middleware;

use Closure;
use App\Client;

class CheckHeaders
{
    public function handle($request, Closure $next)
    {
    ...

    return $next($request);
    }
}

在bootstrap/app中,我添加了

$app->routeMiddleware([
'client' => App\Http\Middleware\CheckHeaders::class,
]);

并将中间件附加到路由:

$router->get('api/tokens', ['middleware' => 'client'], 'TokensController@index');

当我尝试改用外观时

Route::get('api/tokens', 'TokensController@index')->middleware('client');

这次错误是Call to undefined method Laravel\Lumen\Routing\Router::middleware()

我不确定它在 Lumen 中是否与我之前所做的不同,但现在出现错误

Undefined variable: closure
...
in RoutesRequests.php (line 286)

在两个参数而不是三个参数中尝试这样

 $app->get('api/tokens', [
      'middleware' => 'client'
      'as' => 'tokens', 
      'uses' => 'TokensController@index'
  ]);